console: bind methods from the prototype chain in Console

In 62232361 we made the console.Console function construct an object
with methods from Console.prototype bound to the instance, instead of
with methods found on the prototype chain to be bound on the instances,
thus breaking users overriding these methods when subclassing Console
because they are not expecting this function to construct a
namespace whose methods are not looked up from the prototype
chain.

This patch restores the previous behavior since it does not affect
the characteristics of the global console anyway. So after this patch,
the Console function still constructs normal objects with function
properties looked up from the prototype chain but bound to the
instances always.

PR-URL: https://github.com/nodejs/node/pull/24047
Reviewed-By: John-David Dalton <john.david.dalton@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

2 files changed, 10 insertions, 1 deletions

diff --git a/lib/console.js b/lib/console.js
index 2e56f7bbba..39e55c202c 100644
--- a/lib/console.js
+++ b/lib/console.js
@@ -129,7 +129,10 @@ function Console(options /* or: stdout, stderr, ignoreErrors = true */) {
   var keys = Object.keys(Console.prototype);
   for (var v = 0; v < keys.length; v++) {
     var k = keys[v];
-    this[k] = Console.prototype[k].bind(this);
+    // We have to bind the methods grabbed from the instance instead of from
+    // the prototype so that users extending the Console can override them
+    // from the prototype chain of the subclass.
+    this[k] = this[k].bind(this);
   }
 }
 
diff --git a/test/parallel/test-console-instance.js b/test/parallel/test-console-instance.js
index 87708808a8..e6e1e0db24 100644
--- a/test/parallel/test-console-instance.js
+++ b/test/parallel/test-console-instance.js
@@ -105,10 +105,16 @@ out.write = err.write = (d) => {};
 {
   class MyConsole extends Console {
     hello() {}
+    // See if the methods on Console.prototype are overridable.
+    log() { return 'overridden'; }
   }
   const myConsole = new MyConsole(process.stdout);
   assert.strictEqual(typeof myConsole.hello, 'function');
   assert.ok(myConsole instanceof Console);
+  assert.strictEqual(myConsole.log(), 'overridden');
+
+  const log = myConsole.log;
+  assert.strictEqual(log(), 'overridden');
 }
 
 // Instance that does not ignore the stream errors.